Stalin appointed as General Secretary of the Party, giving him a strong position to make alliances and control promotions and demotions; he could connect with regional party organs effectively
Georgian Affair
Stalin brutally suppressed the Georgians and enforced their joining the USSR
Stalin's Role in Lenin's Medical Regime
Stalin was in charge of Lenin's medical care, resulting in Lenin's isolation
Lenin requested cyanide, and Stalin reported this to the Kremlin
Stalin discovered Lenin's Testament and harshly rebuked Krupskaya using brutal language